Safety fence

ABSTRACT

An electrically operated safety fence which is designed to protect workers from the moving parts of an electrically powered machine and consists of a series of base plate sections which are fastened to the floor about the hazard. The base plate sections have sockets which are vertically oriented to removably receive fence sections thereon and to vertically support the fence sections. The base plate sections act as raceways for electrical circuitry wiring and the sockets contain switches which are wired into the electrical circuit. The switches are functioned by the installation or removal of the fence sections. The electrical circuitry of the base plate section switches is wired in series with the electrical power circuit of the machine which functions the moving parts so that when a section of the fence is removed, its associated switch will be activated to automatically interrupt current to the machine.

' United States Patent [191 Foster, Jr.

[4 1 Oct.-14, 1975 1 SAFETY FENCE Joseph E. Foster, Jr., PO. Box 262,Exton, Pa. 19341 [76] Inventor:

[52] US. Cl. 192/133; ZOO/61.58 R [51] Int. Cl F16? 31/00 [58] Field ofSearch 256/1, 24, 59, 21, 22;

74/608, 612; 340/280, 272, 273, 276, 274; 200/61.58 R, 52 R, 85 R, 294,296, 329, 340;

[56] References Cited UNITED STATES PATENTS 1,229,473 6/1917 Keenan200/61.58 R X 1,781,061 11/1930 l-loneycutt 192/133 FOREIGN PATENTS ORAPPLICATIONS 289,180 12/1915 Germany 192/133 Primary ExaminerDennis L.Taylor Attorney, Agent, or FirmWeiser, Stapler & Spivak ABSTRACT Anelectrically operated safety fence which is designed to protect workersfrom the moving parts of an electrically powered machine and consists ofa series of base plate sections which are fastened to the floor aboutthe hazard. The base plate sections have, sockets which are vertically"oriented 'to removably receive fence sections thereon and to verticallysupport the fence sections. The base plate sections act as raceways forelectrical circuitry wiring and the sockets contain switches which arewired into the electrical circuit. The switches are functioned by theinstallation or removal of the fence sections. The electrical circuitryof the base plate section switches is wired in series with theelectrical power circuit of the machine which functions the moving partsso that when a section of the fence is removed, its associated switchwill be activated to automatically interrupt current to the machine.

11 Claims, 4 Drawing Figures U.S. Patent Oct. 14, 1975 SAFETY FENCEBACKGROUND OF THE INVENTION The invention relates generally to the fieldof safety devices, and more particularly is directed to an electricallyactuated safety fence suitable for installation above the moving partsof industrial machines.

Industrial accidents frequently occur in conjunction with movingmechanical apparatus such as power transmission belts, shafts, pulleys,fly wheels, crank shafts and similar normally moving pieces of machineequipment. In order to prevent injury to workers, safety measures ofvarious complexities have been employed in the past. Various types ofbelt guards, fences, shields and other more or less permanent andsophisticated types of equipment have been designed and installed in aneffort to reduce the number of accidents. Generally satisfactory resultshave been achieved during the routine function of the machinery and. theday to day activities within the plant. However, experience has shownthat when a piece of machinery malfunctions for any reason and it isnecessary for a worker to approach the machine in close proximity forthe purpose of adjustment or repair, then such workers are unusuallysusceptible to injury by the faulty equipment. It has been found that inorder to make the required repairs or adjustments, a worker generallyhas to remove the existing safety device or guard. Usually, theequipment switch is moved to the of position so that no injury frommoving machine parts can result. However, it'has been found thatsometimes, through inadvertence, either the switch is not moved to theoff position or else the switch is unintentionally reactivated, therebygiving rise to the possibility of accidents.

SUMMARY OF THE INVENTION The present invention relates generally to thefield of electrical interlocks, and more particularly, is directed to asafety fence construction which is wired into the machine operatingcircuit in a manner to automatically stop the machine operation uponremoval of any portion of the fence material.

The safety fence of the present invention incorporates a series of baseplate sections which are fastened to the floor to form a physicalbarrier about the machine to be protected. The base plate sectionsinclude wire ways through which conventional branch circuit wires can berun in a protected manner to conform to usual electrical constructionsafety standards, such as the requirements of the National ElectricalCode, NFPA No. 70.

The base plate sections are equipped with sockets on predeterminedcenters and each section is equipped with at least one pressure switchwhich is wired in series with the machine control circuit of themachinery or hazard to be protected. Cooperating fence sections fit intothe sockets and serve the dual purpose of acting as a barrier about themachine and of functioning the pressure switches to a closed position tomaintain circuit continuity. Should a fence section be removed, theassociated pressure switches will open to automatically and rapidly shutoff the machine operating circuit to thereby prevent possible injury toan operator. If desired, an alarm circuit can be conventionally wiredinto the safety fence circuit to sound an alarm, operate an annunciatoror function any other similar type of control or alarm equipment.

The safety'fence of the present invention has been designed to complywith the regulations of the Department of Labor promulgated under theOccupational Health and Safety Act as specified in Occupational Safetyand Health Standards, Sub-part O entitled Machinery and MachineGuarding" and particularly with reference to Section 1910.219.

It is therefore an object of the present invention to provide animproved safety fence of the type set forth.

It is another object of the invention to provide a novel safety fence toprotect workers from the moving parts of electrically operated machinesand which includes switch contacts wired in series with the machineoperating circuit for machine control purposes.

It is another object of the present invention to provide a novel safetyfence to protect workers from moving parts of a machine and whichincorporates a series of base plate sections capable of being fastenedto the floor about the machine for accommodating branch circuit wiringand control switches which are wired into the machine operating circuit.

It is another object of the present invention to provide a novel safetyfence for protecting the working parts of a machine which includes aplurality of base plate sections which are fastened to the floor aboutthe machine, the base plate sections being provided with sockets toreceive fence sections in removable arrangement and which furtherinclude switches functioned by the base plate sections to control theoperation of the machine main electrical circuit.

It is another object of the present invention to provide a novel safetyfence incorporating a plurality of base plate sections, each sectionbeing equipped with an upstanding socket to receive a fence sectionthereon, each base plate section being equipped with a pressureactivated switch which is positioned to be controlled by the applicationor removal of a fence section relative to the socket.

It is another object of the present invention to provide a novel safetyfence including a plurality of base plate sections, each sectionincorporating an end positioned socket and a switch in verticalalignment below the socket, the socket receiving a fence section thereinfor switch control purposes, the said switches being wired in serieswith a machine circuit to electrically deactivate the machine when afence section is removed from its association with a socket.

It is another object of the present invention to provide a novel safetyfence that is inexpensive in manufacture, simple in installation andtrouble free when in use.

Other objects and a fuller understanding of the invention will be had byreferring to the following description and claims'of a preferredembodiment thereof, taken in conjunction with the accompanying drawingswherein like reference characters refer to similar parts throughout theseveral views and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing asafety fence constructed in accordance with the present invention andinstalled about a machine to be protected.

FIG. 2 is an enlarged, partial, elevational view looking from line 2-2of FIG. 1, and partially broken away to expose details of interiorconstruction.

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2, lookingin the direction of the arrows, and

partially broken away to expose details of interior construction.

FIG. 4 is an electrical schematic diagram of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Althoughspecific terms are used in the following description for the sake ofclarity, these terms are intended to refer only to the particularstructure of my invention selected for illustration in the drawings andare not intended to define or limit the scope of the invention.

Referring now to the drawings,.l show in FIG. 1, a safety fence lconstructed in accordance with the invention and installed in a mannerto protect a worker (not shown) from the moving parts of mechanicalequipment 12 which may include potentially dangerous components such as,for example, exposed gears, belts, pulleys, shafts, or the like. Aplurality of base plate sections 16 position directly upon the surfaceof the floor 14 and preferably are secured in place in well known mannerby suitable fasteners, such as by employing expansion bolts (notillustrated). The base plate sections 16 support vertical fence sections18 which serve the dual purposes of functioning base plate enclosedswitches in the manner hereinafter more fully set forth and also inpreventing workers from gaining access to the machinery 12 while themachinery is operating.

Referring now to FIGS. 2 and 3, I show each base plate section 16terminating endwardly in a support member 20 which is bolted orotherwise securely affixed to the top surface 22 of the base platesection 16. Each support member 20 comprises a base 24 upon which aresupported a pair of vertical sockets 26 which open upwardly to receivethe fence sections 18 in the manner hereinafter more fully set forth.

The top surface 22 of the base plate section 16 and the base 24 of thesupport member 20 are drilled or otherwise machined to receive theoperators 28 of a pressure activated switch 30 therethrough. Thepressure activated switches 30 are of the normally open type whichfunction to prevent the flow of current therethrough unless the switchoperators 28 are depressed. All of the the switches are wired in serieswith the motor 32 of the machine 12 which is being protected so that theopening of any switch 30 will function to stop the flow of current tothe machine motor. See FIG. 4. The vertical socket 26 preferably isfabricated of steel round tubing of 1% inch outside diameter and 1 /2inch inside diameter. The sockets 26 may be welded or otherwise securelyaffixed to the base 24 in well known manner to provide a secure andrugged assembly. As illustrated in FIG. 1, sufficient base platesections 16 are employed in end to end relationship to preventunauthorized access to the machinery 12 when equipped with the fencesections 18.

The switches 30'are securely mounted to the top surface 22 of the baseplate section 16 in conventional manner such as by employing suitablelock nuts 34 to provide a sturdy installation and to assure that theswitch operators 28 always project upwardly above the top surface of thesupport member bases 24 at the sockets thereof. Preferably, theoperators 28 are oriented in concentric relationship within eachvertical socket 26.

Each fence section 18 is fabricated to a generally U- shapedconfiguration having an upper web section 36 and a pair of legs 38, 40integrally depending therefrom. The fence section framing is preferablyfabricated of carbon steel round tubing of 1 /2 inch outside diameterand inch wall thickness to provide adequate strength and to snugly fitwithin a vertical socket 26. The space defined within the web and thedepending legs is conventionally closed by wire screening of suitablestrength to prevent trespass. Each leg 38, 40 terminates downwardly in abottom plug 42 which is welded or otherwise secured to the bottomterminus 44, 46 of each respective depending leg 38, 40. Each plug 42comprises a flat steel plate that is approximately ls inch in thicknessand 1% inches in diameter to completely close the bottom opening of eachleg. The legs 38, 40 are sized to be a sliding fit within the verticalsockets 26.

As best seen in FIGS. 2 and 3, when a fence section 18 is applied to abase plate section 16 by sliding the respective depending legs 38, 40into base plate associated vertical sockets 26, the weight of the fencesection 18 acts downwardly to seat each fence section securely at thebottom of each respective vertical socket 26 so that the bottom plugs 42contact the switch operators 28. The switches 30 are of the pressureactivated type with normally open contacts. The action of the bottomplugs 42 upon the switch operators 28 acts to respectively close eachswitch 30 by pressing downwardly on each switch operator 28 until itsassociated switch closes. Removal of a fence section 18 from itsassociation with a base plate section 16, such as might occur when it isdesired to enter the machinery enclosure area 48 for maintenance orservice of the machinery 12, will automatically open the correspondingswitch 30 by removal of the bottom plugs 42 from its association withthe switch operator 28. Removal of the pressure applied by the bottomplugs 42 will cause the pressure activated switches 30 to return totheir normally open position, thereby interrupting the flow ofelectrical current to the machinery motor 32.

In order to use the safety fence of the present invention, the baseplate sections 16 are first securely affixed about the machinery 12 tobe protected. A series circuit 50 (FIG. 4) is then established about themachinery 12 to control the machinery motor 32. Circuit wires 52 arewired in series with the machinery motor 32 and the various pressureactivated switches 30 in well known manner. The wires 52 are run withinthe sections 16 which serve as wire raceways for mechanical protectionof the circuit wires. A conventional motor control switch 54 is alsowired in series in the series circuit 50 to conventionally control theoperation of the machinery 12. Thus, in order for the machinery 12 to beoperative, the motor control switch 54 and all of the pressure activatedswitches 30 must be closed. Accordingly, the removal of any fencesection 18 from its association within a socket 26 will release theassociated switch operator 28 which projects upwardly within the socket26 to thereby open its pressure activated switch 30 to automaticallyopen the machinery circuit 50. The interruption of the flow of currentin the circuit 50 inactivates the machine motor 32, thereby preventingthe possibility of injury.

To gain access to the machinery 12 without the necessity of actuallyremoving a fence section 18, it may be desirable to provide a gatesection 56 which could conventionally be of a horizontal swinging type.In this instance, a gate interlock 58 could conventionally be providedand wired into the series circuit 50 (FIG. 4) in a manner to open theseries circuit 50 as soon as the gate section 56 is pivoted from itsclosed position. Thus, should anyone attempt to enter the machineryenclosure area 48 either by removing a fence section 18 or by opening agate section 56, the switches 30, 58 will function to open the machinerycircuit 50 and to automatically and positively deenergize the machinerymotor 32, thereby preventing industrial accidents which may result whena workman contacts a moving piece of the machinery 12.

Although I have described my invention with a certain degree ofparticularity, it is understood that the present disclosure has beenmade only by way of example and that numerous changes in the details ofconstruction and in the combination and arrangement of parts may beresorted to without departing from the spirit and scope of the inventionas hereinafter claimed.

I claim:

1. In a safety fence for protecting a worker from contacting machinerywhich is functioned by an electrical motor, the combination of A. aplurality of base plate sections affixed about the machinery,

1. said base plate sections having an elongated configuration andterminating transversely in a first end and a second end and upwardly ina top surface,

2. said base plate sections being arranged in end to end juxta positionabout the machinery;

B. support members associated with the base plate sections,

1. each support member including a hollow socket and means to hold thesocket in a generally vertical orientation to receive a portion of afence section therein,

a. each hollow socket terminating upwardly in an open end and downwardlyin a bottom end;

C. a plurality of switches secured to the base plate sections invertical alignment with the support members,

1. each switch including a switch operator and switch contacts,

2. each switch operator projecting upwardly into a hollow socket at thebottom end thereof;

D. a control circuit including circuit wires, the electrical motor andthe switches,

1. each said switch being wired into the circuit to control theoperation of the electrical motor in response to function of itsassociated switch operator,

Efand a plurality of fence sections removably attachable to the supportmembers at the sockets thereof,

1. each fence section carrying means to function a switch operator.

2. The invention of claim 1 wherein the switch contacts are normallyopen and are wired in series with the electrical motor.

3. The invention of claim 2 wherein each base plate section isfabricated to an inverted, generally U-shaped configuration to define aninterior space, the said interior space enclosing a portion of thecircuit wires and the switches therein.

4. The invention of claim 3 wherein the means to hold the socketincludes a flat base upon which the socket is affixed, said base beingsecured to the top surface of the base plate section.

5. The invention of claim 4 wherein each base and its associated topsurface of the base plate section are provided with openings, saidopenings being in vertical alignment.

6. The invention of claim 5 wherein each switch operator projectsupwardly into the hollow socket through the aligned openings.

7. The invention of claim 6 wherein each fence section is fabricatedwith a bent frame member which is bent to an inverted U-shapedconfiguration, said frame member including an upper web and a pair oflegs depending therefrom, said legs terminating downwardly respectivelyin a bottom terminus.

8. The invention of claim 7 wherein each bottom terminus insertsdownwardly into a hollow socket through the said open end thereof.

9. The invention of claim 8 wherein each bottom terminus is pusheddownwardly within a socket a sufficient distance to contact a switchoperator.

10. The invention of claim 9 wherein the means to function a switchoperator are affixed to a said bottom terminus.

11. The invention of claim 10 wherein the means to function a switchoperator comprises a bottom plug, said bottom plug being positioned tocontact a switch operator when a bottom terminus is inserted into ahollow socket.

1. In a safety fence for protecting a worker from contacting machinerywhich is functioned by an electrical motor, the combination of A. aplurality of base plate sections affixed about the machinery,
 1. saidbase plate sections having an elongated configuration and terminatingtransversely in a first end and a second end and upwardly in a topsurface,
 2. said base plate sections being arranged in end to end juxtaposition about the machinery; B. support members associated with thebase plate sections,
 1. each support member including a hollow socketand means to hold the socket in a generally vertical orientation toreceive a portion of a fence section therein, a. each hollow socketterminating upwardly in an open end and downwardly in a bottom end; C. aplurality of switches secured to the base plate sections in verticalalignment with the support members,
 1. each switch including a switchoperator and switch contacts,
 2. each switch operator projectingupwardly into a hollow socket at the bottom end thereof; D. a controlcircuit including circuit wires, the electrical motor and theswitches,
 1. each said switch being wired into the circuit to controlthe operation of the electrical motor in response to function of itsassociated switch operator, E. and a plurality of fence sectionsremovably attachable to the support members at the sockets thereof, 1.each fence section carrying means to function a switch operator.
 2. saidbase plate sections being arranged in end to end juxta position aboutthe machinery; B. support members associated with the base platesections,
 2. each switch operator projecting upwardly into a hollowsocket at the bottom end thereof; D. a control circuit including circuitwires, the electrical motor and the switches,
 2. The invention of claim1 wherein the switch contacts are normally open and are wired in serieswith the electrical motor.
 3. The invention of claim 2 wherein each baseplate section is fabricated to an inverted, generally U-shapedconfiguration to define an interior space, the said interior spaceenclosing a portion of the circuit wires and the switches therein. 4.The invention of claim 3 wherein the means to hold the socket includes aflat base upon which the socket is affixed, said base being secured tothe top surface of the base plate section.
 5. The invention of claim 4wherein each base and its associated top surface of the base platesection are provided with openings, said openings being in verticalalignment.
 6. The invention of claim 5 wherein each switch operatorprojects upwardly into the hollow socket through the aligned openings.7. The invention of claim 6 wherein each fence section is fabricatedwith a bent frame member which is bent to an inverted U-shapedconfiguration, said frame member including an upper web and a pair oflegs depending therefrom, said legs terminating downwardly respectivelyin a bottom terminus.
 8. The invention of claim 7 wherein each bottomterminus inserts downwardly into a hollow socket through the said openend thereof.
 9. The invention of claim 8 wherein each bottom terminus ispushed downwardly within a socket a sufficient distance to contact aswitch operator.
 10. The invention of claim 9 wherein the means tofunction a switch operator are affixed to a said bottom terminus. 11.The invention of claim 10 wherein the means to function a switchoperator comprises a bottom plug, said bottom plug being positioned tocontact a switch operator when a bottom terminus is inserted into ahollow socket.